[PPC64LE] Run some existing Altivec tests on powerpc64le as well

There are several Altivec tests that formerly ran only on big-endian
targets (and in some cases only on 32-bit targets).  It is useful to
verify these on little-endian targets as well.

While testing these, I discovered a typo in <altivec.h>.  This is also
fixed by this patch.

llvm-svn: 210928
diff --git a/clang/lib/Headers/altivec.h b/clang/lib/Headers/altivec.h
index bee9e2d..7a4a774 100644
--- a/clang/lib/Headers/altivec.h
+++ b/clang/lib/Headers/altivec.h
@@ -4194,7 +4194,7 @@
 vec_pack(vector bool int __a, vector bool int __b)
 {
 #ifdef __LITTLE_ENDIAN__
-  return (vector unsigned short)vec_perm(__a, __b, (vector unsigned char)
+  return (vector bool short)vec_perm(__a, __b, (vector unsigned char)
     (0x00, 0x01, 0x04, 0x05, 0x08, 0x09, 0x0C, 0x0D,
      0x10, 0x11, 0x14, 0x15, 0x18, 0x19, 0x1C, 0x1D));
 #else